Riveting process



Oct. 6, 1953 w, w, WARREN 2,654,272

RIVETING PROCESS Filed July 16, 1949 III I x \x\\\\\\ 9 uw 8 H u: 9 v H 10 g; FIG! falter: W1), Warren %/%WZZW%WA@ Patented Oct. 6, 1953 RIVETIN G PROCESS Walter Wallace Donald Warren, Montreal, Quebec, Canada Application July 16, 1949, Serial No. 105,168

1 Claim.

This invention relates to improvements in the art of riveting.

A particular feature of this invention is in the provision of a snap or die having an annular working face merging into a sharp pointed centrally protruding punch. The surface of the face may be either fiat, concave or convex depending on the required shape of the rivet head.

Another feature of this invention lies in the provision of a relatively shallow indentation or cavity located in the central portion of the unheaded end of the rivet to be deformed for the reception therein of the protruding punch of the snap or die. The cavity is to be used in conjunction with the snap or die for centering same with respect to the rivet and for assisting in the flow of metal during the riveting operation.

Proceeding now to a more detained description, reference will be had to the accompanying drawings, in. which:

Fig. 1 is a sectional view showing a plurality of plates or work pieces riveted together in accordance with this invention. This view also shows one of the riveting dies or snaps which constitutes an essential novel feature of the invention.

Fig. 2 is a view showing how the snap or die is engaged with the end of the rivet during the early stages of the heading operation. I

Fig. 3 is a plan view of the working face 01' one of the snaps or dies.

.Fig. 4 is a sectional View showing a modified snap or die.

Fig. 5 is a sectional view showing another modified form of snap or die.

Conventional cold riveting, as heretofore practised, has been a machine operation performed in the shop by heavy pressure riveting machinery. No manual cold riveting either in a shop or in the field has been practical with the conventional cold riveting methods in sizes of A and over.

One advantage of the present invention is that, by virtue of the design of the snap or die provided in accordance with the invention, the force required to drive and form the head of a rivet is reduced to a sufiicient extent to enable a cold rivet to be driven or headed by an operator using a hand pneumatic riveting gun equipped with the improved snap or die.

Another advantage is that, while the force required to drive and form the head is reduced to a suflicient extent to enable a cold rivet to be driven, by virtue of the design of the snap or die suflicient force is transmitted to expand the rivet shank to completely fill the rivet hole in the plates.

Another advantage of the invention is that the head formed by improved snaps or dies has less height in cramped positions than the conven--- tional heads formed by the'riveting operations now in use. In this connection it will be noted that the head formed by improved snaps or dies can have either annular, flat, concave or convex top surface surrounding a central inwardly extending cone-shape recess which tapers to a point or are.

Another advantage of the invention is that the snap or die produces a type of rivet which may be advantageously used in place of fitted and/or turned belts in both shop and field practice where adequate filling of the holes by the shanks of the rivets is necessary to ensure maximum shear and bearing values in a joint. In this connection, the present invention enables all rivets to come into stress at the same moment.

Another advantage of the present invention is that the improved type of rivet formed by the novel snap or die provided in accordance with this invention makes it possible, in most instances, to dispense with the heating of field and shop rivets, thus saving both labor and fuel.

Another advantage of the invention is that it makes possible the satisfactory cold driving of rivets made from steel, aluminum and various other metals and alloys.

Referring more particularly to the drawings,

it will be noted that the improved snap or die 4, providedin accordance with this invention, is formed with a tapered face 5, of convex conical shape, merging with a central punch 6 which, in the present instance, is shown as having the shape of a circular cone which is sharply pointed at its outer end. However, it may be noted at this point that the shape of the cone '6 is subject to considerable variation. In this connection, it is pointed out that the punch fi may have the shape of a pyramid, a star-shaped point or any other suitable shape which, when the punch is driven into a rivet cavity 1, will both centre the die and pierce the rivet and, at the same time, cause an outward flow of the metal of the rivet in a lateral direction and also a downward flow to fill the rivet hole completely.

In the use of this invention the plates or work pieces 8 which are to be riveted together are provided with rivet holes 9 through which the rivets It are passed. Ashere shown, each rivet is provided with a conventional head ll against which the backing up or bucking tool is placed during the riveting operation.

As shown more clearly in Fig. 2, the rivetv opening 9 provided in the plate 8, beyond which. 7

the unheaded end of the rivet is initially projected, is countersunk at its outer end to provide a tapered recess I2. Fig. 2 also shows the unheaded end of the rivet drilled and countersunk in the central portion to provide a cavity I. Cavity is shown to be relatively shallow but greater in depth than the length of punch 6. The outer or upper section of the cavity is: conically tapered asihdi'cate'd at fa, toward a ver tically disposed cylindrical mid-section 1b and the bottom section of the cavity is conically tapered to a point from the lower end of the cylindrical mid-section, as indicated at 16 sav ity l is so designed as to cause an initial outward flowin of the rivet metal" hy the punch as the punch descends to the bottom of the cavity. After the punch has struck the stir-filiallolittii'ii 1a of the cavity, the main upsetting operation begins. However, the initial flowing of the metal around the cavity, due to the descending pressure ofltljlesnap; relieves the" shock of contact beta/centhe? punch and i'i'v'et and" facilitates the mainupsetting operatibn or the" unheaded pertionoffthe rivet in its initial stage.

The best results are obtained when the depth oiicavity' l is such that thepunch' pierces the hottom of'the'" cavity" shortly after the beginning of the upsettjing'. operation: The snap or die 8 is" placed against the end of therivet to' be upset andis operated by. means of a recipr'dcatpercussioirliammerwhich causes the punch B' to perietrateltlieiend of the rivet and to drive theymetal? of the rivet outwardly and downwardly. The'woriingracefls'iof thesn'ap or die is highl'y pollshed sotli'at, when this'por'tion of e the snap-ordieacdntacts the rivet; it allows the metal to flow laterallyj under the displacement action of th'e pun'ch Siarid; at the same time,

provides acompressing'sur'face whereby them'etal may he compressed; onto the face ofithe" adjacent plat'e fliliyc'ircula'r rotation of the percus sion hammer. In" this" connection" it will be understood that. theiconve'x workirig' surface 5" cular cantileverfoif metal surrounding" thecentral' opening form'edldyithe'metalfdisplacirigfpunch s.

The pointed? tip of theipunch ress pierfces' the:

metalat the hotto'mof the cavity oii'th'e rivet andtherehy decreases thefresistanceof. the metal lar shoulder cc serves'toiliriiit theoutwardfiow Fig. 5" shows a. further modification which consists of a concave anii'ula'r' face sa" which converge ar'cua'tely withithe punch 6'.- The outwardf flaring portion" of the concave face Ed" is terminated in the annular? shoulderat; When punch 6" is driven tolpenetrate "the rivet in the cavity, the metal is 'causedte new outwardly and:

4 upwardly along the polished arcuate path of the snap face 5a and then downwardly along the flaring ortion to the shoulder 6a. Shoulder 6a serves to limit the outward flow of the rivet metal in a lateral direction. The resulting rivet head formed by the concave faced snap has an annular convexly curved top surface surrounding a central inwardly extending cone-shaped cavity.

I claim:

A riveting process which comprises forming, in the end of the rivet shank remote from the new; a" central punch receiving cavity having a conical inner portion tapering to a point in the direction of the head of the rivet, an intermediate cylindrical portion and an outer conical porfiiorf-fia i i'rlg outwardly from said intermediate portion; the depth of said cavity being predetermined'with reference to the thickness of the work so that, when the rivet is passed through the rivet receiving" opening in the work with the head of the rivet bearing against one side of the? work, a; portion of the rivet s'hanklyifig' inwardlyof'the inner end of thefcavit'y will preject' beyond the a osite side of the work, passing' the rivet thro'u'g'h the said work until the head of the rivet bears against one" side of the work and'theii headingthe cavity containmg end of the rivet sh'a'nk' by forcing thereag'ainst a headihgr'fdie presenting" a entral puhc'li' tapering to'a'poi'iit andsurro'uhdedhyan annmarwvbrmng face inclining outwardly and upwardly from the base of the'punch;saidpurich beiii'gof-a length less than the total'length idf said eavay' na having a" base diameter g r'eat'erthari the" dialriieter ofthe'ihner' end ofthe o'uter'co'nical portion of I the cavity; saidfdie" bei'ng ih'itially' arranged with the punchl fitted the outer" clinical poi"- tion of the cavity and with the wearing race of the diebearing against theend surface 'o'ithe' shank bordering" thecav'ity, and forcing. of; the die against the cavity containing" ehdof the shank until the material of the" shahk' at the inner e'ndof said c'av'ity' is'pierce'd by the punch.

; 1rrance- May's; 1932 

